Recording-type DVD disks, consisting of a DVR+R as a recordable-type DVD disk and a DVD+RW as a rewritable-type DVD disk, etc., have high playback compatibility with a single-side single-layer playback-only DVD disk. Research and development activities for increasing the speed and the capacity of these recording-type disks have been actively carried out.
One of the recording-type disks as described above is a single-side dual-layer recordable DVD+R disk (below abbreviated as “a dual-layer DVD+R”) having playback compatibility with a single-side dual-layer playback-only DVD disk. The dual-layer DVD+R with a recording capacity of 8.4 GB has almost twice the recording capacity of a conventional single-layer DVD+R with a recording capacity of 4.7 GB, and data recorded can be read out with a DVD player or a DVD-ROM drive enabled to reproduce data from the single-side dual-layer playback-only DVD disk.
Now, for the single-side dual-layer playback-only DVD disk, there are two types of track-path techniques, a Parallel Track Path (PTP) technique in which both the second-layer track and the first-layer track start at the inner radius and end at the outer radius, and an Opposite Track Path (OTP) technique in which the second-layer track starts at the outer radius and ends at the inner radius. In the PTP technique, the radial positions of the start addresses of the data areas of the first and the second layers are the same, both starting from a physical address of 30000H. Moreover, following the data area, a lead-out area is arranged. In the OTP method, the radial position of the start address of the second-layer data area is equal to the radial position of the end address of the first-layer data area, the physical address of the start position of the second-layer data area being an address in which the end address of the first-layer data area is bit-inverted. When there is a difference between the sizes of the first layer and the second layer data areas, the differential area becomes the lead-out area. For example, in a PTP disk, when the first-layer data-area end-address D1 and the second-layer data-area end-address D2 are such that D1>D2, the differential area D1-D2 becomes the lead-out area. Thus, the area having data recorded in the first recording layer also has data recorded in the corresponding area of the second layer. This is to avoid an occurrence of a problem such as not being able to obtain address information because data are not recorded at the identical radial position in the second layer, for example, at the time user tries to reproduce the first-layer data, and the reading laser happens to focus on the second layer while in a seek for a target address, resulting in the first-layer data not being able to be reproduced.
Furthermore, logical addresses in the dual-layer DVD are assigned continuously from the start address of the first-layer data area so that the logical addresses are continuous from the end address of the first-layer data area to the start address of the second-layer data area. In other words, when the user reproduces from the dual-layer DVD, designating a reproducing area using the logical addresses enables reproducing without needing to be aware of the recording layers.
Next, a process of recording when user data are recorded in the dual-layer DVD+R is described. In the DVD+R, for the user to record data, an initial-data area is preset so that the physical addresses are assigned in the same manner as the playback-only dual-layer DVD across the extent of the initial-data area. When data are recorded into such a dual-layer DVD+R, the user uses the logical addresses to designate the recording area in the same manner as the reproducing process. Therefore, when the user performs data recording continuously, the recording is started from the start address of the first-layer data area and, once the recording has been completed up to the end address of the first-layer data area, the recording is continued from the start address of the second-layer data area. Thus, even in the dual-layer DVD+R recording, the user is enabled to perform a recording without being aware of the recording layer.
Thus, it is possible that the data recording of the user terminates in the middle of the second-layer data area or without recording on the second layer at all. For example, when the data recording of the user is completed in the middle of the second-layer data area or in a state with an unrecorded area existing within the second-layer data area, it results in a disk layout being incompatible with the playback-only dual-layer DVD disk as described when an unrecorded area within the second-layer data area remains. Moreover, a problem arises such as not being able to obtain the address information because data are not recorded at the identical radial position in the second layer, for example, at the time the user tries to reproduce the first-layer data, and the reading laser happens to focus on the second layer while in a seek for the target address, resulting in the first-layer data not being able to be reproduced. Such problems apply in the same manner when the data recording of the user terminates without recording at all in the second layer.
On the other hand, as an example application of such a dual-layer DVD+R, there is a case in which it is used for test writing before mass producing the playback-only DVD disk. Normally, the data to be recorded in the DVDs, etc., are prepared on a hard disk. Subsequently, the data are recorded in an information-recording medium reproducible with a conventional player in order to validate whether the data have been prepared as data to be reproduced as intended by the preparer. As it is sufficient that the information-recording medium to be used for this validating task be of a small capacity, an information-recording medium recordable only once such as the DVD+R, etc., is often used. However, in the past, as the dual-layer recording disk had not existed, for the playback-only dual-layer DVD disk, the test writing in the recording-type DVD disk for validation could not be performed. Therefore, as described in Patent Document 1, a playback-only dual-layer DVD disk having arranged in the second layer temporary file management information is proposed. In the Patent Document 1 is described a validation process in which test writing is performed per recording layer for different recording disks so that the disk having recorded data in the second layer has the recording data referred to according to the temporary file information.
Thus, the example in the Patent Document 1 is such that the file format of the mass-produced playback-only dual-layer DVD itself is modified and in the validation process two recording-type DVD disks are recorded for validating the recording data per layer, making producing of a disk having a data structure completely identical to the playback-only DVD to be produced so as to perform a validation impossible. Moreover, in the validation according to the example in the Patent Document 1, the validation of data recorded on the second layer is performed according to the temporary file management information, making validation of the data recorded on the second layer from the file management information recorded on the first layer impossible.
Patent Document 1
JP2000-048542A
Now, while some process for the unrecorded area is considered to be necessary in order to avoid the problem of causing the unrecorded area as described above, a derivative problem arises in which, for instance, when the recording of the user data is completed with the second-layer data area almost unrecorded, or when the data recording is completed with no user data recorded at all in the second layer, etc., it results in a large unrecorded area so that a long time is required for the process of handling the unrecorded area.
Moreover, as for the validation, etc., as described above concerning the example application of the dual-layer DVD+R, while it is possible to resolve the problems as described above concerning the validation, etc., when using the dual-layer DVD+R, even in this case, in the dual-layer DVD+R, an initial-data area is preset for the user to record the data in, so that in order to record in a data format completely identical to the playback-only DVD to be produced, means for setting as the data area a random area out of the preset initial-data area is required, although a countermeasure concerning this point has yet to be proposed.